Personal computer (“PC”) card technology is used in mobile computing platforms. The PC card family includes 16-bit PC cards to serve the needs of modest performance and older (legacy) PC card applications, as well as the 32-bit PCI-like CardBus PC cards used to satisfy the most demanding of today's computing add-in needs. As portable platforms continue to diversify in form-factor and decrease in power consumption, add-in card technologies need to reflect the compact and energy-efficient portable host systems in which they are used. Mobile systems need user-installable, modular add-in capability, in both card and storage form-factors, in order to support standardized system configuration for corporate information technology departments and rapidly changing application domains, such as Internet-based processing.
Mobile systems are also evolving to input/output (“I/O”) technology based on popular serial buses, such as the Universal Serial Bus (“USB”). Accompanying this change is a drive to “layer” future add-in capabilities onto these newer buses. CardBus has been the standard for add-in capabilities for today's PCI-based systems. However, as USB gains popularity, a new PC card standard has been required. CardBay has emerged as that standard. CardBay offers the expected set of PC card functions, along with enhancements that meet the changing needs of mobile technology, while maintaining backward compatibility to legacy PC cards.
CardBay is an implementation of USB devices at a CardBus card socket. CardBay essentially substitutes a USB interface for the existing CardBus interface while retaining the CardBus physical connector and PC card format. Therefore, instead of inserting a CardBus card into a CardBus socket, a user can insert a CardBay (USB 1.1 or USB 2.0) card into the CardBus socket. However, there are problems related to using a CardBay card in a CardBus socket. One major problem is the routing of USB ports through CardBus. A second major problem is that USB does not inherently “talk” with CardBus PCMCIA/PCI drivers (i.e., the USB driver stack is not related to the PCMCIA or PCI driver functions). Other problems related to using a Cardbay card in a CardBus socket are: recognizing when a CardBay card is present, knowing which USB port to enable, sending an “enable” command for the boot sequence, and USB stack interoperability.
To date, these problems have only been addressed through hardware solutions. For example, one hardware solution runs a switch between the USB chip and the CardBus chip, allowing for physical power on and off of the device. A second hardware solution allows for the addition of four (4) pins to the CardBus pins, isolating the CardBus chip from CardBay. There are currently no software solutions addressing the problems related to using a CardBay card in a CardBus socket. A software solution could be implemented at relatively low costs, would not require any space modifications, and can work without modifications to existing operating systems.
It is therefore desirable to provide a solution that enables the use of a CardBay card in a CardBus socket at a relatively low cost, without requiring space modifications, and capable of working without modifications to existing operating systems. Exemplary embodiments of the present invention can provide this by the inclusion of a filter driver capable of communicating with the USB stack and controller and with the CardBay, CardBus, and flashmedia stack and controller.